The Dallas Morning News [irritating registration procedure required] reports that Mark Thatcher's return to Dallas has been delayed "indefinitely" because of an "immigration snag" in Germany:

An acquaintance in Britain said Friday, however, that Mr. Thatcher's        return will be delayed indefinitely because of immigration problems he        encountered in Frankfurt, Germany, where he stopped en route to Dallas.

His passport was seized upon his arrest, and in the meantime, the        acquaintance said, Mr. Thatcher's U.S. visa expired. So he will remain        in Frankfurt while his attorneys negotiate with U.S. authorities. The        source said such negotiations could take days, weeks or even months.

The acquaintance said the plea bargain was for the equivalent of a        misdemeanor – not a felony – and they expected no problem in his        eventually returning to the United States.

However, Marie Sebrechts, an official with U.S. Citizenship and        Immigration Services in Southern California, said Mr. Thatcher's fate        rests with the U.S. State Department, the only agency that can issue him        a visa.

"In the way things are being evaluated right now," said Ms. Sebrechts,        "his connections or position shouldn't have any impact – it's pretty        much a blind system at this point. Whatever he did or was charged with        is all that will be considered. The question becomes, does it make him        admissible or not admissible?"    

MEANWHILE, Gregory Wales denies that he is to be extradited to South Africa. From the Guardian:

The last remaining unconvicted Englishman of those accused of plotting an African coup last night denied that he was to be extradited.

Greg Wales, who remains at liberty in west London following the conviction of Sir Mark Thatcher and mercenary Simon Mann, said through his lawyers that those who had pleaded guilty "obviously had their own reasons for entering into arrangements with the South African authorities".

South Africa says it will continue its investigations thanks to Sir Mark's full cooperation, and sources there have reported that Mr Wales may be a target for extradition attempts. 

Recall that Wales is the fellow who met with Theresa Whelan, US  Deputy Assistant Secretary of Defense for African Affairs, in February and advised her of the coming coup.